std::experimental::scope_fail

 

C++

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Technical Specifications

 

Technical specifications

Filesystem library (filesystem TS)

Library fundamentals (library fundamentals TS)

Library fundamentals 2 (library fundamentals TS v2)

Library fundamentals 3 (library fundamentals TS v3)

Extensions for parallelism (parallelism TS)

Extensions for parallelism 2 (parallelism TS v2)

Extensions for concurrency (concurrency TS)

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Library fundamentals v3

experimental::scope_exit

experimental::scope_fail

experimental::scope_success

experimental::unique_resource

 

std::experimental::scope_fail

Member functions

scope_fail::scope_fail

scope_fail::~scope_fail

Modifiers

scope_fail::release

Deduction guides

 

Defined in header <experimental/scope>
template<class EF> class scope_fail;		(library fundamentals TS v3)

The class template scope_fail is a general-purpose scope guard intended to call its exit function when a scope is exited via an exception.

scope_fail is not CopyConstructible, CopyAssignable or MoveAssignable, however, it may be MoveConstructible if EF meets some requirements, which permits wrapping a scope_fail into another object.

A scope_fail may be either active, i.e. calls its exit function on destruction, or inactive, i.e. does nothing on destruction. A scope_fail is active after constructed from an exit function.

A scope_fail can become inactive by calling release() on it either manually or automatically (by the move constructor). An inactive scope_fail may also be obtained by initializing with another inactive scope_fail. Once a scope_fail is inactive, it cannot become active again.

A scope_fail effectively holds an EF and a bool flag indicating if it is active, alongwith a counter of uncaught exceptions used for detecting whether the destructor is called during stack unwinding.

Template parameters

EF	-	type of stored exit function
Type requirements
- EF shall be either: a Destructible FunctionObject type an lvalue reference to FunctionObject an lvalue reference to function
- Calling an lvalue of std::remove_reference_t<EF> with no argument shall be well-formed.

Member functions

(constructor)	constructs a new scope_fail (public member function)
(destructor)	calls the exit function when the scope is exited via an exception if the scope_fail is active, then destroys the scope_fail (public member function)
operator= [deleted]	scope_fail is not assignable (public member function)
Modifiers
release	makes the scope_fail inactive (public member function)

Notes

Constructing a scope_fail of dynamic storage duration might lead to unexpected behavior.

Constructing a scope_fail is constructed from another scope_fail created in a different thread might also lead to unexpected behavior since the count of uncaught exceptions obtained in different threads may be compared during the destruction.

See also

scope_exit	wraps a function object and invokes it on exiting the scope (class template)
scope_success	wraps a function object and invokes it on exiting the scope normally (class template)
default_delete (C++11)	default deleter for unique_ptr (class template)